Brown discharge

So yesterday I had a very long day. We drove two hours to go to a bday party and then some family’s house and went swimming. I was so exhausted when I got home and when I went to the bathroom I noticed a little bit of light brown discharge on my underwear and on the toilet paper when I wiped. It was very little and haven’t had anymore since... no cramping but still makes me worried. I’m 6 weeks today and wondering if it’s normal? I was thinking maybe I overdid it yesterday? Or could it possibly be from swimming???